Tube flaring apparatus



Oct. 20, 1970 J. s. sTAslEK 3,534,572

TUBE FLARING APPARATUS Filed 0G11. 13, 1967 2 Sheets-Sheet 1 'im' v 75 f3 JW, 5. m

f fraz/vega Oct. 20, 1970 J. s. sTAslEK 3,534,572

TUBE FLARING APPARATUSy Filed Oct. 13, 1967 2 Sheets-Sheet United States Patent O r? ce 3,534,572 TUBE FLARING APPARATUS .lan S. Stasiek, Altadena, Calif., assigner, by mesne assignments, to Torque Controls, Inc., El Monte, Calif., a corporation of California Filed Oct. 13, 1967, Ser. No. 675,214 Int. Cl. BZld 41/02 U.S. Cl. 72-36 15 Claims ABSTRACT OF THE DISCLOSURE Four segments of a chuck grip a tube and form four quadrants of a female flaring die, the four segments being spring biased to retract and being individually connected to four corresponding radial hydraulic rams which operate under high pressure to insure close mating of the female die quadrants. A conical male aring die which serves as an adjustable stop for a newly inserted tube and is operated by a fifth hydraulic ram, cooperates with the female die and places the metal of the tube end under sufcient pressure for plastic forming of the metal as distinguished from mere mechanical forming.

BACKGROUND OF THE INVENTION There is pressing need for an efficient method of producing high-precision flared tube joints and especially in the space industry where a crew of men is required to take care of leaks at each launching pad. In one instance it cost about one hundred thousand dollars to take care of sixtyseven leaks.

One common type of tube-flaring apparatus employs rollers for a metal spinning operation but it has been found that rollers do not create uniform flow of the metal that is being worked and do not produce perfectly round iiared surfaces. The bearings are inevitably inaccurate to some degree to result in non-uniform pressure and the creation of residual stresses. It has been observed, furthermore, that at the beginning of a flaring operation by rollers the flared metal is out of round and, in fact, is elliptical because the initial force is applied at one point or at most at two diametrically opposite points. It is only at the end of the rolling operation that the elliptical conguration is ironed out to result in an approximatetly circular configuration and even then the metal tends to spring back when it is finally released from the pressure of the rollers.

Another type of tube-Haring apparatus in current use is a hydraulic apparatus employing a chuck divided into four segments that close to grip a tube and to form four quadrants of a female liaring die. Hydraulic means closes the chuck and drives a conical male flaring die axially to carry out the tube iiaring operation. Examples of such prior art tube aring devices are found in the following patents: Hartley 2,438,999; Hull 2,464,510; Hull 2,478,- 102; and Parker 2,480,762.

One of the problems encountered in designing a tube flaring apparatus of this second type resides in the fact that the four segments of the chuck must close to some given inside diameter for the purpose of forming the surface of the female flaring die and therefore, the chuck will grip all sizes of tubes within a given range of tolerance only if the inside diameter of the closed chuck is the minimum outside diameter of the tubes within the range f tolerance. All of the tubes except the tubes of minimu-m outside diameter will necessarily be more or less damaged by the chuck.

Another problem is the diiiiculty of matching or mating the four quadrants of the female die with sufficient accuracy. When two adjacent chuck segments fail to close perfectly, a radial rib is formed on the back or outer sur- 3,534,572 Patented Oct. 20, 1970 face of the iiared end of the tube. When a male tube fitting is tightened to make a joint with such a ribbed tube end, the resulting compression across the thickness of the liared metal tends to transfer the rib from the outer surface of the ared tube to the inner surface where the sealing action takes place and the result is a faulty seal.

It has been found that an inherent defect of a tube flaring apparatus disclosed in each of the four above mentioned patents is that the four segments of the chuck are operated by a hydraulically actuated cam ring that cooperates with tapered outer surface of the chuck segments and especially so because the hydraulic force is transmitted to the cam ring at circumferentially spaced points with consequent deformation of the cam ring.

A further problem confronting the industry is that a tube flaring apparatus now employed for producing liared tube ends of high quality is a relatively massive machine, the cost of which is on the order of one hundred and fifty thousand dollars. Such a machine employs rotating parts, bushings, bearings and other components that tend to create inaccuracies and especially so under wear. Different dies are used for different sizes and types of tubes and a changeover from one tube to another is a tedious time-consuming procedure involving microscopic inspection of samples in preparation for a production run. Such a machine represents a large capital investment and the overall rate of production is relatively low in proportion to the capital investment.

A further disadvantage of the large expensive machines such as currently employed is that the big jaws of a machine cannot grip an end of a tube that is near a bend in the tube. A set of tubes in a jet engine, for example, has numerous complex bends and requires flared tube ends that are relatively near some of the bends.

The object of the present invention is to avoid the above-mentioned disadvantages of prior art tube flaring machines. The invention teaches that a highly accurate tube aring apparatus may be produced at relatively low cost for operation at a relatively high production rate.

SUMMARY OF THE INVENTION The invention employs a hydraulically actuated chuck in cooperation with a hydraulically operated axially movable male flaring die, the chuck being divided into four segments which not only grip a tube for a aring operation but also four separate quadrants of a female ilaring die. The hydraulic pressure required for a coining operation at which the metal becomes fluid is in the range of 90,000 to 150,00 p.s.i. For this purpose the invention utilizes hydraulic fluid under pressure that may be as high as 5,000 p.s.i., with an area differential capable of creating an applied pressure by the male die as high as 20,000 p.s,L

Instead of employing a cam ring, the invention provides four radially positioned hydraulic rams respectively to control the four segments of the chuck. Highly accurate matching of the four quadrants of the female flaring die is achieved, in part, by applying a given high magnitude of fluid pressure to each of the four chuck segments independently of the other segments; in part, by providing highly accurate radial guide Ways for the four chuck segments and, finally, by forming the four chuck segments with highly accurately ground mating wedge surfaces. To provide accurate guide ways for the four segments, the four segments are integral with the pistons of the four corresponding hydraulic rams and the cylinders of the four hydraulic rams are bored in a single -block of metal. The guide way for the axially movable male flaring die is also a bore in the same metal block.

A feature of the described arrangement is that the application of equal exceedingly high hydraulic pressure t0 the four chuck segments independently causes the four chuck segments to seek positions at which the four highmagnitude forces are in precise equilibrium. The female die quadrants are not only precisely matched at this equilibrim but also are under such high pressure across each of the four junctures of the segments that the metal is in effect continuous across each juncture.

The problem of designing the segmental chuck to grip tubes of a range of outside of diameters within a given dimensional tolerance is met by designing the chuck to close to a diameter slightly larger than the outside diameter of a tube of the maximum dimension within the given range of tolerance and by providing each chuck segment with a uid-pressure-responsive means to extend radially inwardly suiciently to grip tubes of diameters less than the maximum diameter. This concept may be embodied in various ways. In the preferred practice of the invention each chuck segment has a bore occupied by an elastomeric body and when hydraulic pressure is applied to close the chuck each of the elastomeric bodies is deformed by hydraulic pressure into engagement with a tube in the chuck.

The problem of minimizing the time required to change over from processing tube ends of one nominal size to processing tubing ends of a different nominal size is solved by providing different embodiments of the apparatus for the different nominal tube sizes. A further change over problem remains, however, in that tubes of a given nominal outside diameter may be made of different metals and may be of different inside diameters. The invention meets this further change over problem by making the male forming die adjustably retractable to serve as an adjustable stop for newly inserted tubes, suitable index means being provided for use with the adjustable stop. Preferably, but not necessarily, the index means is in the form of a micrometer in the path of retraction of the piston that carries the male flaring die. Once a reading of the micrometer has been attained for flaring a tube made of a given material with a given inside diameter, the micrometer may be used to duplicate the same stop setting without loss of time at any future time.

The various features and advantages of the invention may be understood by reference to the following detailed description and the acccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to be regarded as merely illustrative FIG. 1 is a diagram incorporating a rear elevational View of the presently preferred embodiment of the invention;

FIG. 2 is a longitudinal section taken along the line 2 2 of FIG. l;

FIG. 3 is a fragmentary sectional view longitudinally of one of the four radial pistons showing how a fluidpressure-responsive elastomeric body may be incorporated in the piston construction;

FIG. 4 is a fragmentary section transversely of the axis of the chuck showing how the four elastomeric bodies cooperate to grip a tube that is of smaller outside diameter than the inside diameter of the closed chuck;

FIG. 5 is an elevational view of the four segments of the chuck with the surrounding structure removed to show how the four chuck segments close together at equilibrium positions; and

FIG. 6 is an enlarged fragmentary sectional view showing a tube end in the chuck after the tube end has been flared.

DESCRIPTION OF THE PREFERRED EMBODIMENT As may be understood 4by reference to FIG. 2, a single block of metal, generally designated 10, provides a passage 12 to receive a tube end that is to be flared and has four bores 14 forming four cylinders which are positioned radially of the passage 12 at 90 apart. The four chuck segments are in the form of four pistons 15 and the four radial cylinders cooperate with the four pistons to serve as accurate guide ways for the four chuck segments. The block of metal 10 is further bored and counterbored to form a guide way 16 for a conically nosed male flaring die 18 and to form a relatively large cylinder 20 in which is mounted a piston 22 that carries and actuates the male die. The piston 22, which is embraced by an O-ring 24, has an axial stern or shank 25 in the form of a cap screw with a washer 28 backed against the head 30 of the tap screw. The large cylinder 20 is closed -by a hollow cylinder head 32 which is secured to the metal block 10 by screws 34 with the joint sealed by an O-ring 35.

The hydraulic system includes a pipe 36 that is connected to the cylinder head 32 by a fitting 38 and the outer end of the cylinder head is bored and counterbored to embrace a micrometer 40 having an adjustable axially movable gauge element 42. The micrometer 40 is anchored with sullicient effectiveness to withstand the high fluid pressure and is embraced by a suitable `O-ring 44.

As may be seen in FIG. 2, the large piston 22 is biased by a coil spring to back the head 30 of the piston stem 25 into abutment with the gauge element 42. In the construction shown, the piston stem 25 extends through an apertured disk 46 that is anchored in place by the cylinder head 32. The disk 46 serves as a seat for the coil spring 45, the coil spring acting in compression between the seat and the washer 28.

As shown in FIG. 3, each of the four radial pistons 15 is embraced by an O-ring 50 and as shown in FIG. 2 each piston is provided with an axial stem or shank 52 that extends into a corresponding cylinder head 54. Each of the four cylinder heads 54 is releasably secured to the metal block 10 in a suitable manner and is sealed by a corresponding O-ring 55. Each of the four radial cylinder heads 54 is connected by a corresponding fitting 56 t0 a corresponding pipe 58 of the hydraulic system.

Each of the four radial pistons or chuck segments 15 is biased outward to a normal retracted position as shown in FIG. 2. For this purpose a coil spring 60 in each radial cylinder head 54 acts in compression between a seat in the form of a disk 62 and a washer 64 that backs against a hexagonal head 65 of the corresponding stem 52. Each of the disks 62 is anchored in place by the corresponding cylinder head 54.

The inner end of each of the four radial chuck segments 15 is formed with two faces 72 (FIG. 3) inclined at an angle of 45 relative to the path of the chuck segment. When the four chuck segments 70 close together around a tube 74, they form a female die having an annular ared die surface 75, each chuck segment forming one quadrant of the female die.

In the construction shown, each of the chuck segments 15 is provided with an axial bore 716 as indicated in FIG. 3 and a suitable body 78 of elastomeric material occupies the bore and preferably is bonded to the inner wall of the bore. To provide uid communication between the axial bore 76 and the interior of the corresponding radial cylinder 1-4, corresponding stern 52 of the piston is provided with an axial bore 80 and an intersecting diametrical bore 82.

When the four pistons 15 are driven radially inwardly by high hydraulic pressure, the chuck segments 70 formed by the inner ends of the pistons close tightly together to form the female flaring die and the interactions of the chuck segments at their mating inclined wedge faces 72 causes the chuck segments to seek equilibrium positions with respect to the four radial hydraulic forces at Awhich equilibrium positions the four quadrants of the female die match perfectly with ex ceedingly high interface pressure so that the metal of the female die is in effect continuous across each juncture between two faces 72.

As indicated diagrammatically in FIG. 1, a suitable hydraulic system for the tube Haring apparatus includes a source of high pressure hydraulic fluid indicated by the block 84 which supplies hydraulic fluid to a first control valve 85 and a second control valve 86. The first control valve 85 controls flow simultaneously through the four hydraulic lines 58 to the four radial cylinders 14 and the second control valve 86 controls flow through the hydraulic line 36 to the large cylinder 20. Each of the two control valves is connected to a corresponding low pressure return line 88. The two control valves 85 and 86 may be operated by handles 90 and 92, respectively, or may be adapted for remote control by push buttons or may be operated by a suitable sequential control.

The manner in which the apparatus serves its purpose may be readily understood from the foregoing description. When the various moving parts are in their normal positions, the position of the retracted male flaring die 18 is determined by the adjustment of the micrometer 4@ which has a setting for a given tube size and the four radial chuck segments 15 are fully retracted to positions indicated by the dotted lines 94 in FIG. 2. The open chuck not only provides clearance for a new tube to be inserted into the chuck but also provides room for a flared tube to be withdrawn through the chuck.

A newly inserted tube is moved against the conical nose of the male flaring die 18 as shown in FIG. 2 and is thus positioned correctly relative to the female die for the desired flaring operation. The first control valve 85 is operated to admit high pressure hydraulic fluid to the four radial cylinders 14 to force the four chuck segments 15 to their closed positions shown in solid lines in FIG. 3, the four segments of the chuck being in equilibrium for matching the four quadrants of the female flaring die with high precision. In some instances, the inner ends of the four chuck segments 15 grip the newly inserted tube but in most instances the inner diameter of the closed chuck is slightly larger than the newly inserted tube and the four elastomeric bodies 78 of the radial pistons are distorted by fluid pressure into gripping engagement with the newly inserted tube. The second control valve 92 is then operated to admit high pressure hydraulic fluid into the large cylinder 20 to thrust the male flaring die 18 towards the female die with consequent flaring of the newly inserted tube end.

With the hydraulic fluid at a pressure on the order of 5,000 p.s.i., the four chuck segments 70 effectively immobilize the newly inserted tube. With the same pressure in the cylinder 20 multipled by the relatively large area of the piston 22, the male flaring die 18 flares the tube end by plastic formation of the metal as distinguished from mechanical formation. After the newly inserted tube is flared in this manner, the two control valves 85 and 86 are operated to place the various hydraulic cylinders in communication with the low pressure return lines 88 whereupon the coil springs 60 return the four radial pistons 15 to their normal retracted positions and the coil spring retracts the male forming die 18 and the associated piston 22 to their normal positions as determined by adjustment of the micrometer 40.

My description in specific detail of the presently preferred embodiment of the invention 'will suggest various changes, substitutions and other departures from my disclosure within the spirit and scope of the appended claims.

I claim:

1. In a tube flaring apparatus, the combination of:

means forming a passage to receive a tube end;

a plurality of segment members having die portions cooperative to form a flared female die in alignment with said passage;

a corresponding plurality of guideways positioned radially of said passage to guide the segment members respectively;

a corresponding plurality of hydraulic actuating means paired with said segment members respectively and operatively connected thereto respectively to force 6 the segment members inwardly from normal retracted lpositions along said guideways into said passage to closed positions to form said female die; means to energize said plurality of hydraulic means simultaneously; and a power-actuated male flaring die movable along the axis of said passage towards said female die to flare a tube end adjacent the female die.

2. A combination as set forth in claim 1 in which the power means for actuating the male flaring die generates sufficient pressure for plastic forming of the flared end of the tube.

3. A combination as set forth in claim 1 in which said guide'ways are formed in a single metal body.

4. A combination as set forth in claim 3 in which said metal body is formed with a fifth guideway for said male flaring die positioned coaxially of the female die.

5. A combination as set forth in claim 1 in which said segment members are segments of a chuck to grip a tube end in said passage.

6. A combination as set forth in claim 2 which includes Imeans on each of said chuck segments responsive to the corresponding hydraulic means to extend inward from the chuck segment at the closed position thereof into gripping engagement 'with a tube in Said passage.

7. A combination as set forth in claim 2 in which said male flaring die is adjustable over a range of retracted positions to serve as a stop for locating newly inserted tube ends at predetermined positions in said passage.

8. In a tube flaring apparatus, the combination of:

a support structure forming a passage to receive a tube end that is to be flared;

four cylinders arranged radially of said passage apart and opening into said passage; four pistons in said four cylinders respectively, the inner ends of said pistons being tapered with pairs of faces inclined at 45 to the axes of the pistons,

the inner ends of said pistons forming mating quadrant portions of a female flaring die;

a fifth cylinder lpositioned coaxially of said passage;

a fifth piston in said fth cylinder;

a male flaring die projecting from the fifth piston lo cooperate with the female flaring die;

means to supply fluid under pressure to said four cylinders equally to drive said pistons inwardly to close the pistons together with balanced centering action among the inclined faces of the four pistons for accurate mating of the four quadrant portions of the female flaring die; and

means to supply fluid under pressure to said fifth cylmder to actuate said male die to cooperate with said female die for flaring a tube end in said passage.

9. A combination as set forth in claim 8 which includes means to bias said four pistons towards radially outward retracted positions to clear a flared tube in said passage.

10. A combination as set forth in claim 8 which includes means to retract said male flaring die in the absence of fluid pressure in said fifth cylinder.

11. A combination as set forth in claim 8 in which all of said cylinders are bores in a `single metal body.

12. A combination as set forth in claim 8 in which said pistons form a segmental chuck to grip a tube in said passage.

13. A combination as set forth in claim 12 in :which means is mounted on each of said pistons to extend longitudinally inwardly therefrom into engagement with a tube in said passage in response to fluid pressure in the four cylinders when the pistons fail to engage an undersized tube at the inner limit position of the pistons.

14. A combination as set forth in claim 13 which includes a first control means to admit fluid under pressure from a common source into said four cylinders simultaneously;

and which includes a second control means to admit fluid under pressure into the fth cylinder.

15. fIn a tube aring apparatus, the combination of a support structure forming a passage to receive a tube end;

a power-actuated chuck contractible from a normal expanded state to a contracted state to grip a tube in said passage and to form a female flaring die around the tube,

said chuck at its expanded state being of an outside diameter large enough to clear a ared tube;

a male aring die to advance along the axis of said passage towards said chuck to cooperate with said female die for aring a tube end;

hydraulic means to actuate the male flaring die, said hydraulic means including a piston coaxially of the male flaring die rearwardly thereof and connected thereto;

means carried by the piston and extending axially rear wardly therefrom to move in unison with the male flaring die;

a micrometer having a sensing element in the path of Asaid coaxially extending means and positioned coaxially of the axially extending means to cooperate therewith as a stop to determine the retracted position of the male aring die when said piston is not actuated, said sensing means being adjustable by the micrometer along said path; and

spring means to bias said piston and -male flaring die rearwardly to urge said axially extending means against said sensing element when said piston is not actuated.

References Cited UNITED STATES PATENTS 3,393,549 7/196 8 Gregg 72-316 LOWELL A. LARSON, Primary Examiner U.S. Cl. X.R. 

